Struct std::collections::BinaryHeap
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pub struct BinaryHeap<T> {
// some fields omitted
}1.0.0A priority queue implemented with a binary heap.
This will be a max-heap.
It is a logic error for an item to be modified in such a way that the
item's ordering relative to any other item, as determined by the Ord
trait, changes while it is in the heap. This is normally only possible
through Cell, RefCell, global state, I/O, or unsafe code.
Examples
fn main() { use std::collections::BinaryHeap; // Type inference lets us omit an explicit type signature (which // would be `BinaryHeap<i32>` in this example). let mut heap = BinaryHeap::new(); // We can use peek to look at the next item in the heap. In this case, // there's no items in there yet so we get None. assert_eq!(heap.peek(), None); // Let's add some scores... heap.push(1); heap.push(5); heap.push(2); // Now peek shows the most important item in the heap. assert_eq!(heap.peek(), Some(&5)); // We can check the length of a heap. assert_eq!(heap.len(), 3); // We can iterate over the items in the heap, although they are returned in // a random order. for x in &heap { println!("{}", x); } // If we instead pop these scores, they should come back in order. assert_eq!(heap.pop(), Some(5)); assert_eq!(heap.pop(), Some(2)); assert_eq!(heap.pop(), Some(1)); assert_eq!(heap.pop(), None); // We can clear the heap of any remaining items. heap.clear(); // The heap should now be empty. assert!(heap.is_empty()) }use std::collections::BinaryHeap; // Type inference lets us omit an explicit type signature (which // would be `BinaryHeap<i32>` in this example). let mut heap = BinaryHeap::new(); // We can use peek to look at the next item in the heap. In this case, // there's no items in there yet so we get None. assert_eq!(heap.peek(), None); // Let's add some scores... heap.push(1); heap.push(5); heap.push(2); // Now peek shows the most important item in the heap. assert_eq!(heap.peek(), Some(&5)); // We can check the length of a heap. assert_eq!(heap.len(), 3); // We can iterate over the items in the heap, although they are returned in // a random order. for x in &heap { println!("{}", x); } // If we instead pop these scores, they should come back in order. assert_eq!(heap.pop(), Some(5)); assert_eq!(heap.pop(), Some(2)); assert_eq!(heap.pop(), Some(1)); assert_eq!(heap.pop(), None); // We can clear the heap of any remaining items. heap.clear(); // The heap should now be empty. assert!(heap.is_empty())
Methods
impl<T> BinaryHeap<T> where T: Ord
fn new() -> BinaryHeap<T>
Creates an empty BinaryHeap as a max-heap.
Examples
Basic usage:
fn main() { use std::collections::BinaryHeap; let mut heap = BinaryHeap::new(); heap.push(4); }use std::collections::BinaryHeap; let mut heap = BinaryHeap::new(); heap.push(4);
fn with_capacity(capacity: usize) -> BinaryHeap<T>
Creates an empty BinaryHeap with a specific capacity.
This preallocates enough memory for capacity elements,
so that the BinaryHeap does not have to be reallocated
until it contains at least that many values.
Examples
Basic usage:
fn main() { use std::collections::BinaryHeap; let mut heap = BinaryHeap::with_capacity(10); heap.push(4); }use std::collections::BinaryHeap; let mut heap = BinaryHeap::with_capacity(10); heap.push(4);
fn iter(&self) -> Iter<T>
Returns an iterator visiting all values in the underlying vector, in arbitrary order.
Examples
Basic usage:
fn main() { use std::collections::BinaryHeap; let heap = BinaryHeap::from(vec![1, 2, 3, 4]); // Print 1, 2, 3, 4 in arbitrary order for x in heap.iter() { println!("{}", x); } }use std::collections::BinaryHeap; let heap = BinaryHeap::from(vec![1, 2, 3, 4]); // Print 1, 2, 3, 4 in arbitrary order for x in heap.iter() { println!("{}", x); }
fn peek(&self) -> Option<&T>
Returns the greatest item in the binary heap, or None if it is empty.
Examples
Basic usage:
fn main() { use std::collections::BinaryHeap; let mut heap = BinaryHeap::new(); assert_eq!(heap.peek(), None); heap.push(1); heap.push(5); heap.push(2); assert_eq!(heap.peek(), Some(&5)); }use std::collections::BinaryHeap; let mut heap = BinaryHeap::new(); assert_eq!(heap.peek(), None); heap.push(1); heap.push(5); heap.push(2); assert_eq!(heap.peek(), Some(&5));
fn capacity(&self) -> usize
Returns the number of elements the binary heap can hold without reallocating.
Examples
Basic usage:
fn main() { use std::collections::BinaryHeap; let mut heap = BinaryHeap::with_capacity(100); assert!(heap.capacity() >= 100); heap.push(4); }use std::collections::BinaryHeap; let mut heap = BinaryHeap::with_capacity(100); assert!(heap.capacity() >= 100); heap.push(4);
fn reserve_exact(&mut self, additional: usize)
Reserves the minimum capacity for exactly additional more elements to be inserted in the
given BinaryHeap. Does nothing if the capacity is already sufficient.
Note that the allocator may give the collection more space than it requests. Therefore
capacity can not be relied upon to be precisely minimal. Prefer reserve if future
insertions are expected.
Panics
Panics if the new capacity overflows usize.
Examples
Basic usage:
fn main() { use std::collections::BinaryHeap; let mut heap = BinaryHeap::new(); heap.reserve_exact(100); assert!(heap.capacity() >= 100); heap.push(4); }use std::collections::BinaryHeap; let mut heap = BinaryHeap::new(); heap.reserve_exact(100); assert!(heap.capacity() >= 100); heap.push(4);
fn reserve(&mut self, additional: usize)
Reserves capacity for at least additional more elements to be inserted in the
BinaryHeap. The collection may reserve more space to avoid frequent reallocations.
Panics
Panics if the new capacity overflows usize.
Examples
Basic usage:
fn main() { use std::collections::BinaryHeap; let mut heap = BinaryHeap::new(); heap.reserve(100); assert!(heap.capacity() >= 100); heap.push(4); }use std::collections::BinaryHeap; let mut heap = BinaryHeap::new(); heap.reserve(100); assert!(heap.capacity() >= 100); heap.push(4);
fn shrink_to_fit(&mut self)
Discards as much additional capacity as possible.
Examples
Basic usage:
fn main() { use std::collections::BinaryHeap; let mut heap: BinaryHeap<i32> = BinaryHeap::with_capacity(100); assert!(heap.capacity() >= 100); heap.shrink_to_fit(); assert!(heap.capacity() == 0); }use std::collections::BinaryHeap; let mut heap: BinaryHeap<i32> = BinaryHeap::with_capacity(100); assert!(heap.capacity() >= 100); heap.shrink_to_fit(); assert!(heap.capacity() == 0);
fn pop(&mut self) -> Option<T>
Removes the greatest item from the binary heap and returns it, or None if it
is empty.
Examples
Basic usage:
fn main() { use std::collections::BinaryHeap; let mut heap = BinaryHeap::from(vec![1, 3]); assert_eq!(heap.pop(), Some(3)); assert_eq!(heap.pop(), Some(1)); assert_eq!(heap.pop(), None); }use std::collections::BinaryHeap; let mut heap = BinaryHeap::from(vec![1, 3]); assert_eq!(heap.pop(), Some(3)); assert_eq!(heap.pop(), Some(1)); assert_eq!(heap.pop(), None);
fn push(&mut self, item: T)
Pushes an item onto the binary heap.
Examples
Basic usage:
fn main() { use std::collections::BinaryHeap; let mut heap = BinaryHeap::new(); heap.push(3); heap.push(5); heap.push(1); assert_eq!(heap.len(), 3); assert_eq!(heap.peek(), Some(&5)); }use std::collections::BinaryHeap; let mut heap = BinaryHeap::new(); heap.push(3); heap.push(5); heap.push(1); assert_eq!(heap.len(), 3); assert_eq!(heap.peek(), Some(&5));
fn push_pop(&mut self, item: T) -> T
Pushes an item onto the binary heap, then pops the greatest item off the queue in an optimized fashion.
Examples
Basic usage:
#![feature(binary_heap_extras)] fn main() { use std::collections::BinaryHeap; let mut heap = BinaryHeap::new(); heap.push(1); heap.push(5); assert_eq!(heap.push_pop(3), 5); assert_eq!(heap.push_pop(9), 9); assert_eq!(heap.len(), 2); assert_eq!(heap.peek(), Some(&3)); }#![feature(binary_heap_extras)] use std::collections::BinaryHeap; let mut heap = BinaryHeap::new(); heap.push(1); heap.push(5); assert_eq!(heap.push_pop(3), 5); assert_eq!(heap.push_pop(9), 9); assert_eq!(heap.len(), 2); assert_eq!(heap.peek(), Some(&3));
fn replace(&mut self, item: T) -> Option<T>
Pops the greatest item off the binary heap, then pushes an item onto the queue in an optimized fashion. The push is done regardless of whether the binary heap was empty.
Examples
Basic usage:
#![feature(binary_heap_extras)] fn main() { use std::collections::BinaryHeap; let mut heap = BinaryHeap::new(); assert_eq!(heap.replace(1), None); assert_eq!(heap.replace(3), Some(1)); assert_eq!(heap.len(), 1); assert_eq!(heap.peek(), Some(&3)); }#![feature(binary_heap_extras)] use std::collections::BinaryHeap; let mut heap = BinaryHeap::new(); assert_eq!(heap.replace(1), None); assert_eq!(heap.replace(3), Some(1)); assert_eq!(heap.len(), 1); assert_eq!(heap.peek(), Some(&3));
fn into_vec(self) -> Vec<T>1.5.0
Consumes the BinaryHeap and returns the underlying vector
in arbitrary order.
Examples
Basic usage:
fn main() { use std::collections::BinaryHeap; let heap = BinaryHeap::from(vec![1, 2, 3, 4, 5, 6, 7]); let vec = heap.into_vec(); // Will print in some order for x in vec { println!("{}", x); } }use std::collections::BinaryHeap; let heap = BinaryHeap::from(vec![1, 2, 3, 4, 5, 6, 7]); let vec = heap.into_vec(); // Will print in some order for x in vec { println!("{}", x); }
fn into_sorted_vec(self) -> Vec<T>1.5.0
Consumes the BinaryHeap and returns a vector in sorted
(ascending) order.
Examples
Basic usage:
fn main() { use std::collections::BinaryHeap; let mut heap = BinaryHeap::from(vec![1, 2, 4, 5, 7]); heap.push(6); heap.push(3); let vec = heap.into_sorted_vec(); assert_eq!(vec, [1, 2, 3, 4, 5, 6, 7]); }use std::collections::BinaryHeap; let mut heap = BinaryHeap::from(vec![1, 2, 4, 5, 7]); heap.push(6); heap.push(3); let vec = heap.into_sorted_vec(); assert_eq!(vec, [1, 2, 3, 4, 5, 6, 7]);
fn len(&self) -> usize
Returns the length of the binary heap.
Examples
Basic usage:
fn main() { use std::collections::BinaryHeap; let heap = BinaryHeap::from(vec![1, 3]); assert_eq!(heap.len(), 2); }use std::collections::BinaryHeap; let heap = BinaryHeap::from(vec![1, 3]); assert_eq!(heap.len(), 2);
fn is_empty(&self) -> bool
Checks if the binary heap is empty.
Examples
Basic usage:
fn main() { use std::collections::BinaryHeap; let mut heap = BinaryHeap::new(); assert!(heap.is_empty()); heap.push(3); heap.push(5); heap.push(1); assert!(!heap.is_empty()); }use std::collections::BinaryHeap; let mut heap = BinaryHeap::new(); assert!(heap.is_empty()); heap.push(3); heap.push(5); heap.push(1); assert!(!heap.is_empty());
fn drain(&mut self) -> Drain<T>1.6.0
Clears the binary heap, returning an iterator over the removed elements.
The elements are removed in arbitrary order.
Examples
Basic usage:
fn main() { use std::collections::BinaryHeap; let mut heap = BinaryHeap::from(vec![1, 3]); assert!(!heap.is_empty()); for x in heap.drain() { println!("{}", x); } assert!(heap.is_empty()); }use std::collections::BinaryHeap; let mut heap = BinaryHeap::from(vec![1, 3]); assert!(!heap.is_empty()); for x in heap.drain() { println!("{}", x); } assert!(heap.is_empty());
fn clear(&mut self)
Drops all items from the binary heap.
Examples
Basic usage:
fn main() { use std::collections::BinaryHeap; let mut heap = BinaryHeap::from(vec![1, 3]); assert!(!heap.is_empty()); heap.clear(); assert!(heap.is_empty()); }use std::collections::BinaryHeap; let mut heap = BinaryHeap::from(vec![1, 3]); assert!(!heap.is_empty()); heap.clear(); assert!(heap.is_empty());
fn append(&mut self, other: &mut BinaryHeap<T>)
Moves all the elements of other into self, leaving other empty.
Examples
Basic usage:
#![feature(binary_heap_append)] fn main() { use std::collections::BinaryHeap; let v = vec![-10, 1, 2, 3, 3]; let mut a = BinaryHeap::from(v); let v = vec![-20, 5, 43]; let mut b = BinaryHeap::from(v); a.append(&mut b); assert_eq!(a.into_sorted_vec(), [-20, -10, 1, 2, 3, 3, 5, 43]); assert!(b.is_empty()); }#![feature(binary_heap_append)] use std::collections::BinaryHeap; let v = vec![-10, 1, 2, 3, 3]; let mut a = BinaryHeap::from(v); let v = vec![-20, 5, 43]; let mut b = BinaryHeap::from(v); a.append(&mut b); assert_eq!(a.into_sorted_vec(), [-20, -10, 1, 2, 3, 3, 5, 43]); assert!(b.is_empty());
Trait Implementations
impl<'a, T> Extend<&'a T> for BinaryHeap<T> where T: Copy + 'a + Ord1.2.0
fn extend<I>(&mut self, iter: I) where I: IntoIterator<Item=&'a T>
impl<T> Extend<T> for BinaryHeap<T> where T: Ord
fn extend<I>(&mut self, iter: I) where I: IntoIterator<Item=T>
impl<T> IntoIterator for BinaryHeap<T> where T: Ord
type Item = T
type IntoIter = IntoIter<T>
fn into_iter(self) -> IntoIter<T>
Creates a consuming iterator, that is, one that moves each value out of the binary heap in arbitrary order. The binary heap cannot be used after calling this.
Examples
Basic usage:
fn main() { use std::collections::BinaryHeap; let heap = BinaryHeap::from(vec![1, 2, 3, 4]); // Print 1, 2, 3, 4 in arbitrary order for x in heap.into_iter() { // x has type i32, not &i32 println!("{}", x); } }use std::collections::BinaryHeap; let heap = BinaryHeap::from(vec![1, 2, 3, 4]); // Print 1, 2, 3, 4 in arbitrary order for x in heap.into_iter() { // x has type i32, not &i32 println!("{}", x); }